Silica-based PLC demultiplexer with spectral modulation function for monitoring signal wavelengths

A 100 GHz-spacing 48-channel planar lightwave circuit (PLC)-type demultiplexer with a spectral modulation function for monitoring signal light wavelengths is reported. The demultiplexer is composed of a Mach-Zehnder interferometer (MZI) and two arrayed-waveguide gratings. Its centre wavelength can be shifted more than 100 Hz with a modulating signal applied to a thermo-optic heater on the MZI section.